In the manufacture of rotary heat regenerators, it has been considered desirable to form the regenerator matrix of a material having a low heat conductivity to minimize heat transfer between the faces of the regenerator. Synthetic organic plastic materials in film form such as polystyrene, vinyl, polyester or the like have been proposed for such use in applications where the temperature of the gases is not excessive, however a regenerator made of such material has inadequate lateral strength and rotational rigidity unless external reinforcement is provided. The cost of such additional re-inforcement as used in prior types of regenerators would prevent the use of such devices in high volume, low cost applications.